Field of Invention
The present invention relates to wireless communication, and more particular to an antenna device that is capable of changing impedance matching between an antenna element and its related circuit.
Description of Related Art
Wireless communication technology is widely used in various kinds of electronic devices for data or voice transmission. In general, the electronic devices may use some specific wireless communication specifications to perform wireless transmission, such as IEEE 802.11, Bluetooth (BT), wide band code division multiple access (WCDMA) and so on.
However, no matter what type of wireless communication is used, a lot of electromagnetic waves are generated during data transmission, thus harming a user's health. Hence, before being put into the market for sale, the electronic devices with wireless communication function have to pass a specific absorption rate (SAR) test, so as to diminish possible dangers to the user due to the electromagnetic waves.